Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “electromagnetic fields”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,099 records · Page 61Linked to original sources
PubMed1997

Effects of low-intensity AC and/or DC electromagnetic fields on cell attachment and induction of apoptosis.

Rat tendon fibroblast (RTF) and rat bone marrow (RBM) osteoprogenitor cells were cultured and exposed to AC and/or DC magnetic fields in a triaxial Helmholtz coil in an incubator for up to 13 days. The AC fields were at 60 and 1000 Hz and up to 0.25 mT peak to peak, and the DC fields were up to 0.25 mT. At various combinations of field strengths and frequencies, AC and/or DC fields resulted in extensive detachment of preattached cells and prevented the normal attachment of cells not previously attached to substrates. In addition, the fields resulted in altered cell morphologies. When RTF and RBM cells were removed from the fields after several days of exposure, they partially reattached and assumed more normal morphologies. An additional set of experiments described in the Appendix corroborates these findings and also shows that low-frequency EMF also initiates apoptosis, i.e., programmed cell death, at the onset of cell detachment. Taken together, these results suggest that the electromagnetic fields result in significant alterations in cell metabolism and cytoskeleton structure. Further work is required to determine the relative effect of the electric and magnetic fields on these phenomena. The research has implications for understanding the role of fields in affecting bone healing in fracture nonunions, in cell detachment in cancer metastasis, and in the effect of EMF on organisms generally.

Animals↗
PubMed2002

Effect of ultraviolet B radiation and 100 Hz electromagnetic fields on proliferation and DNA synthesis of Jurkat cells.

The use of ultraviolet B light (UVB) has been proven to be highly effective for treatment of various inflammatory skin diseases, but UVB phototherapy is limited by its carcinogenic side effects. It is necessary to uncover effectors that augment UVB so that similar or improved efficacy can be obtained with lower UVB doses. We found that low frequency, low intensity electromagnetic fields (EMFs) can act as such an effector and synergistically inhibit T lymphocyte proliferation. We first characterized the effects of UVB on Jurkat cells, a model for cutaneous T lymphocytes, and determined UVB's dose dependent inhibition of cell proliferation and induction of apoptosis. Cells exposed to a sublethal UVB dose retained their sensitivity to UVB, but repetitive irradiation seemed to cause accumulation of delayed DNA damage. We then exposed cells to combinations of UVB plus EMFs and found that 100 Hz, 1 mT EMFs decrease DNA synthesis of UVB-activated Jurkat cells by 34 +/- 13% compared to UVB alone. The decrease is, however, most effective when relatively high UVB doses are employed. Since EMFs alone had only a very weak inhibitory effect (10 +/- 2%), the data suggest that EMFs augment the cell killing effects of UVB in a synergistic way. These findings could provide the basis for development of new and improved clinical phototherapy protocols.

Apoptosis↗
PubMed1997

Reverse-micelle model: pH, electromagnetic field and inhibitor enzyme interaction.

The reverse micelle is one of many models thought to have properties more nearly resembling the biological cellular environment, than does the traditional dilute-solution biochemical reaction system. In order to evaluate the results of EMF perturbation of enzyme-catalyzed reactions, the description of the AOT reverse-micelle model, with respect to its internal pH, effect of chemical inhibitors, temperature, and electromagnetic-field perturbation has herein been extended. Acetylcholinesterase and NADPH cytochrome-P450 reductase, reacting within the AOT reverse-micelle, exhibit a temperature vs. activity profile equivalent to the same reaction in a buffered dilute-solution environment. In reverse micelles, some inhibitors of AChE (propidium, and d-tubocurarine) have much less effect upon indophenol-acetate hydrolysis than they do in a dilute solution environment. Other inhibitors act in the same manner within the structured environment of the reverse micelle as in the conventional dilute solution reaction model. These differences are explicable in terms of mechanism of action of the individual inhibitors. Perturbation by low-intensity microwave fields has a similar inhibitory effect upon dilute-solution reactions, as those in the 'low-water-activity' environment of the reverse micelle. However, the interactions between physical and chemical perturbants are differently limited by the structure of the aqueous phase of the reverse micelle. pH of the 'internal' reverse-micelle environment is a function of the availability of H-ions supplied by system components. Use of indicator dyes show that the low-molarity buffers which are compatible with reverse-micelle stability, are often insufficient to maintain a constant pH. Too, in the reverse micelle, reaction rate, for proton yielding reactions, is dramatically greater than the rate of the same reaction in dilute solution at the same acidic pH.

Animals↗
PubMed1995

Premenstrual exacerbation of symptoms in multiple sclerosis is attenuated by treatment with weak electromagnetic fields.

It has been suspected that hormonal factors contribute to the etiology and pathogenesis of multiple sclerosis (MS). A direct relationship between MS and endocrine functions is suggested by changes in disease activity during the phases of the menstrual cycle. A subset of women with MS experience premenstrual worsening of symptoms which improve dramatically with the onset of menstruation. The biological mechanisms underlying these changes in disease activity are unexplained but may be related to cyclical fluctuations in gonadal sex steroid hormones, abrupt changes in the activity of the endogenous opioid peptides and fluctuations in plasma melatonin levels which affect neuronal excitability and immune functions. Extracerebral application of weak electromagnetic fields (EMFs) in the picotesla range intensity has been reported efficacious in the treatment of MS with patients experiencing sustained improvement in motor, sensory, autonomic, affective and cognitive functions. The present report concerns two women with chronic progressive stage MS who experienced, coincident with increasing functional disability, regular worsening of their symptoms beginning about a week before menstruation and abating with the onset of menstruation. These symptoms resolved two months after the initiation of treatment with EMFs. The report supports the association between the endocrine system and MS and indicates that brief, extracranial applications of these magnetic fields modifies the activity of neuroendocrine systems which precipitate worsening of MS symptoms premenstrually.

Adult↗
PubMed2003

Pulsed electromagnetic fields affect phenotype and connexin 43 protein expression in MLO-Y4 osteocyte-like cells and ROS 17/2.8 osteoblast-like cells.

Osteocytes, the predominant cells in bone, are postulated to be responsible for sensing mechanical and electrical stimuli, transducing signals via gap junctions. Osteocytes respond to induced shear by increasing connexin 43 (Cx43) levels, suggesting that they might be sensitive to physical stimuli like low-frequency electromagnetic fields (EMF). Immature osteoblasts exhibit decreased intercellular communication in response to EMF but no change in Cx43. Here, we examined long term effects of pulsed EMF (PEMF) on MLO-Y4 osteocyte-like cells and ROS 17/2.8 osteoblast-like cells. In MLO-Y4 cell cultures, PEMF for 8 h/day for one, two or four days increased alkaline phosphatase activity but had no effect on cell number or osteocalcin. Transforming growth factor beta-1 (TGF-beta 1) and prostaglandin E(2) were increased, and NO(2-) was altered. PEMFs effect on TGF-beta1 was via a prostaglandin-dependent mechanism involving Cox-1 but not Cox-2. In ROS 17/2.8 cells, PEMF for 24, 48 or 72 h did not affect cell number, osteocalcin mRNA or osteocalcin protein. PEMF reduced Cx43 protein in both cells. Longer exposures decreased Cx43 mRNA. This indicates that cells in the osteoblast lineage, including well-differentiated osteoblast-like ROS 17/2.8 cells and terminally differentiated osteocyte-like MLO-Y4 cells, respond to PEMF with changes in local factor production and reduced Cx43, suggesting decreased gap junctional signaling.

Alkaline Phosphatase↗
PubMed1995

Present knowledge about specific absorption rates inside a human body exposed to radiofrequency electromagnetic fields.

We have compiled results of scientific investigations about the relationship between external field-strengths and specific absorption rates inside the human body. The data were normalized to SAR-values that form the basis for current safety standards. Results were compared to exposure limits given in these standards. This comparison should serve as a reference for the selection of reliable reference levels for personal protection against thermal effects in radiofrequency electromagnetic fields. The need to measure and monitor ankle/wrist currents to protect some exposed workers is explained. The study has also highlighted a scarcity of dosimetric data at frequencies below 3 MHz.

Dose-Response Relationship, Radiation↗
PubMed2004

Noninvasive treatment of inflammation using electromagnetic fields: current and emerging therapeutic potential.

Magnets, electric current and time varying magnetic fields always have played a role in human medicine. Natural magnetic stones were used in ancient cultures to induce a therapeutic effect and modern clinical practice would be far less effective without nuclear magnetic resonance imaging, cardiac pacemakers, and bone growth stimulators. This paper presents a summary of natural and artificial electromagnetic field (EMF) characteristics that are currently in use or under investigation for other therapeutic applications. This background understanding provides a basis for discussion on the success and possible risks of emerging and novel EMF therapies. Although interest in energy medicine has existed for centuries in some parts of the world, in recent years this is an area of heightened interest for western healthcare practitioners. This awareness has been triggered by the growing body of knowledge on how EMFs interact with cellular systems. EMF therapy for the treatment of pain, cancer, epilepsy, and inflammatory diseases like psoriasis, tendinitis and rheumatoid arthritis is currently being explored. The long-term success of this new area of medicine is still unknown. On the one hand, it remains to be seen whether positive human outcomes with EMF therapy could be explained by enhancement of the placebo effect. Optimistically, EMF therapy has the potential to revolutionize medicine, which is currently dominated by pharmaceutical and surgical interventions. In this case, new therapeutic tools may be developed for future clinicians to provide noninvasive treatments with low risk of side effects and no problem with drug interactions.

Animals↗